Nonequilibrium transport through a quantum dot coupled to normal and superconducting leads

We study the interacting quantum dot coupled to the normal and superconducting leads by means of a continuous-time quantum Monte Carlo method in the Keldysh-Nambu formalism. Deducing the steady current through the quantum dot under a finite voltage, we examine how the gap magnitude in the superconducting lead and the interaction strength at the quantum dot affect transport properties. It is clarified that the Andreev reflection and Kondo effect lead to nonmonotonic behavior in the nonequilibrium transport at zero temperature.Comment: 6 pages, 3 figures, conference paper of SCES 201

Cluster mean-field approach with density matrix renormalization group: Application to the hard-core bosonic Hubbard model on a triangular lattice

We introduce a new numerical method for the solution of self-consistent equations in the cluster mean-field theory. The method uses the density matrix renormalization group method to solve the associated cluster problem. We obtain an accurate critical value of the supersolid-superfluid transitions in the hard-core bosonic Hubbard model on a triangular lattice, which is comparable with the recent quantum Monte Carlo results. This algorithm is applicable to more general classes of models with a larger number of degrees of freedom.Comment: 6 pages, 4 figures, SCES 201